## Circular Orbits

1. The problem statement, all variables and given/known data

If given a speed of a spacecraft, and a radius from the sun, how do you prove that it was or was not in a circular orbit about the sun?

2. Relevant equations

3. The attempt at a solution
To prove it is not do I just find the mass of the spacecraft and the size of its mass will determine this? I am so confused I dont even know where to start?!!
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 Recognitions: Homework Help The problem statement is not well formed, since it presumes that the speed is not radial, in which case the 'orbit' will be degenerate -- the spacecraft will either plummet directly into the Sun or escape straight outwards. So assuming that this is not the case... What do you know about objects in circular orbits around the Sun? Think about how their periods are related to their orbital radii, and how their orbital speeds are related to their periods.